This application claims the priority of German Patent Document No. 101 50 720.8, filed Oct. 13, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates particularly to a system having a unit for controlling a transmission line.
International Patent Document WO 93/10378 A1 discloses a system of the above-mentioned type. The system has a control unit for controlling a transmission line of a motor vehicle, which has a transmission having a first plurality of wheel sets for engaging and disengaging transmission gears and a plurality of shift clutches. The shift clutches can be shifted by the operating units of an operating device. Two shift clutches are combined to form a shift stack, and two non-successive transmission gears are assigned to each shift stack.
An operating unit is assigned to each shift stack, which operating unit can be operated and controlled independently of the operating units of the other shift stacks.
Shifting operations between transmission gears can be controlled such that the shift stacks are operated in an overlapping manner. Simultaneously or immediately successively, a shifted shift clutch can be moved to its neutral position and a shift clutch to be shifted can be moved toward its shifting position. During the upshifting, a shift clutch of a transmission gear higher than the transmission gear to be shifted can be loaded additionally to the shift clutch of the transmission gear to be shifted in order to reduce the speed of a countershaft.
In particular, it is an object of the invention to provide a system of the above-mentioned type by which reduced shifting times can be reached.
The invention is based on a system having a unit for controlling a transmission line, particularly of a motor vehicle. The motor vehicle has a transmission having a plurality of wheel sets for engaging and disengaging transmission gears and having a plurality of shift clutches which can be operated by an operating device for engaging and disengaging transmission gears. At least one shift clutch to be shifted is operable while a shifted shift clutch is still engaged.
The unit for controlling a transmission line guides, at least during one shifting operation, the shift clutch to be shifted to its synchronizing point, while the shifted shift clutch is still engaged. The unit also guides an input clutch of the transmission, at least before the end of a synchronizing operation of the shift clutch to be shifted, into its opening position by way of an actuator. Fast and comfortable shifting operations can be achieved despite a low stressing of the respective shift clutches, and special engaging mechanisms for an engagement under a load can be avoided. The unit should be able to contain a controlling and/or a regulating function.
If during a reduction of the moment at the shifted shift clutch in a shifting operation, the unit brings the shift clutch to be shifted at least to a partial level of a maximal synchronization moment, additional shifting time can be saved.
In a further development of the invention, during a shifting operation, the unit brings the shift clutch to be shifted to the maximum synchronization moment after the disengaging of the previously shifted shift clutch, whereby low loads of the shift clutches can be achieved during the shifting operation. However, under certain conditions, for example, in a kick-down mode, the maximal synchronization moment is already set before the disengagement.
In addition, during a shifting operation, the unit operates the shift clutch to be shifted as a function of a rotational speed of the input shaft of the transmission. A flexible control can be achieved, during which shifting operations can be implemented in accordance with the rotational speed of the input shaft. As a function of the rotational speed of the input shaft, the point in time can be determined at which the shift clutch to be shifted is brought to the synchronous point, when the shift clutch to be sifted is set to a partial level of the maximal synchronization moment, and/or when the maximal synchronization moment is set. In addition, as a function of the rotational speed of the input shaft, the extent of the partial level and/or of the maximal synchronization moment can also be determined. The rotational speed of the input shaft is a value which is very important for the shifting operation. However, the shifting operation may be controlled as a function of other operating parameters, for example, as a function of the rotational speed of an output shaft, of adjusting paths of the input clutch and/or of a shift clutch, of the driving speed, of the transmission oil temperature, of a selected operating program, etc.
If, during a shifting operation, the unit changes a gradient of the moments of the input clutch during its opening operation, shifting time can be saved again, comfort can be increased and the stressing of the shift clutches can be reduced. This may occur specifically when, during the shifting operation, the unit increases at least for a short time an opening speed of the input clutch before its opening position.
Advantageously, during a shifting operation, the unit changes the gradient of the moments of the input clutch as a function of the rotational speed of the input shaft. A flexible control can be achieved during which shifting operations are adapted to the rotational speed of the input shaft. As a function of the rotational speed of the input shaft, the time can be determined at which the gradient is changed and to what extent it is changed. In addition to the rotational speed of the input shaft, the gradient can be changed as a function of other operating parameters, for example, the rotational speed of an output shaft, adjusting paths of the input clutch and/or of a shift clutch, the driving speed, the transmission oil temperature, a selected operating program, etc.
In a further development, during a shifting operation, as a function of a tolerance value, the unit avoids a negative output moment, specifically in the case of upshifts under tension. An undesirable braking of the motor vehicle during the shifting operation can be reliably avoided and comfort can be increased.
If the tolerance value can be set as a function of at least one detected operating parameter, such as the friction lining thickness of the input clutch, transmission oil consistency, transmission oil temperature, service life, etc., a learning system can be obtained, and shifting operations can always be achieved which are optimized corresponding to the conditions.
Furthermore, during a shifting operation between the fifth and the sixth transmission gears, the unit leads the shift clutch to be shifted to its synchronization point, after the previous shifted shift clutch has disengaged. The shift clutches for the fifth and sixth transmission gears may have a standard construction, particularly that of a unit, and a cost-effective compact overall construction can be achieved.
If the operating device has at least one controller cylinder, by way of which the at least two shift clutches can be shifted, space can also be saved and a particularly cost-effective, low weight and space-saving construction can be achieved. If the operating device has at least two actuators, by way of which at least two shift clutches can be shifted, a particularly flexible control can be achieved.
In a further development of the invention, a transmission series is suggested which has a manual transmission and an automatic transmission. In the case of the automatic transmission, wheel sets for the second and the third transmission gear can be arranged in an exchanged manner. At a reasonable cost, a transmission series can be obtained which has a manual and an automatic transmission. In addition, particularly in a simple construction, an automatic transmission can be achieved which is suitable for the system according to the invention. Specifically, one shifting unit can be assigned to the first and the third transmission gear and another shifting unit can be assigned to the second and the fourth transmission gear, or one shifting unit can in each case be assigned to two non-successive transmission gears.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.